ImageMagick convert scan

Text document resize and quality

After scanning a document you may want to resize and compress the resulting image. You should scan with a higher resolution so you can have a better-quality lower resolution.

convert '*.jpg' -set filename:f '%t(resized).%e' -resize 1500x -quality 85 '%[filename:f]'

Text document white threshold

The white paper background will probably not end up being white so we add a 'white-threshold'. A lower value will mean more light areas are converted to pure white.

convert '*.jpg' -set filename:f '%t(resized).%e' -white-threshold 92% -resize 1500x -quality 80 '%[filename:f]'

White threshold

The white paper background will probably not end up being white so we add a 'white-threshold'. A lower value will mean more light areas are converted to pure white.

convert '*.jpg' -set filename:f '%t(resized).%e' -white-threshold 92% -resize 1500x -quality 80 '%[filename:f]'

Split up picture

When you scan all your old photos, four at a time, you can use this to divide them up in quarters.

for file in *.jpg
do
  file_name="${file##*/}"
  file_path="${file%/*}"
  file_basename="${file_name%.*}"
  file_ext="${file_name##*.}"
  #divide picture into quarters with a 4 pixel overlap
  convert "${file}" -crop 2x2+4+4@ +repage +adjoin "${file_basename}_%d.${file_ext}"
done

Also see

• ImageMagick tools